This invention relates to a method of treating dry human skin by the topical administration of certain alkylmethylpolysiloxanes.
The water content of the outer layers of the stratum corneum of human skin is a controlling factor in the appearance of dry skin symptoms. When the stratum corneum contains an adequate amount of water within the range of ten to twenty percent the skin remains flexible. However when the water content falls below ten percent the stratum corneum often becomes brittle and rough and can exhibit scaling and cracking.
The stratum corneum receives its water from the deep layers of the epidermis by diffusion or when it is brought into direct contact with water. The diffusion process is controlled by the water content of the skin as well as the concentration gradient. In a very dry environment the water loss from the external skin layers can be significant and often exceeds the rate of replacement by diffusion. An occlusive barrier placed onto the surface of the skin acts to retard the water loss to the environment and allows the skin to rehydrate by the diffusion process.
The convenient availability and low cost of nonprescription drugs and over-the-counter medicines has spawned an increase in responsible consumer self-medication in the field of dry skin treatment. Numerous dry skin preparations are available. Typical dermatological moisturizers containing one or more emollients can be found marketed under trademarks such as EUCERIN.RTM. and NIVEA.RTM. by Beiersdorff Incorporated, Norwalk, Conn.; KERI.RTM. by Westwood Pharmaceuticals Incorporated, Buffalo, N.Y.; LUBRIDERM.RTM. by Warner-Lambert Company; and NEUTROGENA.RTM. by Neutrogena Corporation, Los Angeles, Calif.
The present invention provides a dry skin preparation containing certain alkylmethylendblocked polysiloxanes which has been found to alleviate the symptoms of dry skin more effectively than some of the currently available over-the-counter dermatological formulations. While alkylmethylendblocked siloxanes are known in the prior art as evidenced by U.S. Pat. Nos. 3,632,619 issued Jan. 4, 1972; 3,756,052 issued Sep. 4, 1973; and 4,973,476 issued Nov. 27, 1990; their use in the treatment of dry skin in the fashion contemplated by the present invention is not disclosed.